1. Field
An aspect of the present invention relates to a display device, and more particularly, to a display device having an increased aperture ratio and an external black matrix with a reduced width.
2. Description of the Related Art
Liquid crystal display (LCD) devices are light-weight, thin, and function under low driving power consumption, and thus are widely used as a display device for laptop computers or portable televisions (TV).
The LCD displays a desired image on a screen by adjusting a transmission amount of light according to a signal applied to multiple control switches that are arranged in a matrix.
FIGS. 1 and 2 are plan views illustrating a structure of a liquid crystal panel 100 in a conventional LCD.
Referring to FIGS. 1 and 2, the liquid crystal panel 100 includes a plurality of pixel areas P formed of a plurality of gate lines GL1 through GLn and a plurality of data lines DL1 through DLm. Each pixel area P includes a thin film transistor (TFT) T, a liquid crystal capacitor Clc, and a storage capacitor Cst.
In the TFT T, a gate electrode 10 is connected to the gate lines GL1 through GLn, a source electrode 20 is connected to the data lines DL through DLm, and a drain electrode 30 is connected to a pixel electrode 40.
The liquid crystal capacitor Clc is connected to the TFT T and is driven by an electrical field between the pixel electrode 40 and a common electrode (not shown). The arrangement of liquid crystal particles in a liquid crystal layer of the liquid crystal capacitor Clc is changed by an electrical field when a common voltage is applied to a common voltage (Vcom) line so as to adjust the amount of light being transmitted or to block light.
The storage capacitor Cst is driven by a part of the pixel electrode 40 and a predetermined area of active level shift (ALS) lines ALSL1 through ALSLn that are parallel to the gate lines GL1 through GLn. An ALS driving unit 130 applies an ALS voltage Va to the ALS lines ALSL1 through ALSLn.
When a high gate voltage Vgh is applied to the gate electrode 10 of the TFT T to turn on the TFT T, and then a data voltage Vd is applied to the pixel electrode 40, the storage capacitor Cst is charged to a charge amount corresponding to a voltage difference between the data voltage (pixel voltage) Vd and the ALS voltage Va. The charge amount in the storage capacitor Cst is supplied to the pixel electrode 40 that is floated while the TFT T is turned off as a low gate voltage Vgl is applied to the gate electrode 10 of the TFT T, thereby allowing the liquid crystals to be continuously driven.
In a single bank gate type liquid crystal panel as described above, a gate driver 110 for driving the pixel electrode 40 and an ALS driver 130 used to reduce power consumption are disposed in black matrix (BM) areas on left and right outer portions of the liquid crystal panel 100. In a double bank gate type liquid crystal panel, a gate driver 110 connected to odd-numbered gate lines on a left portion of an outer BM of the liquid crystal panel 100 and an ALS driver 130 connected to even-numbered ALS lines are included, and another gate driver 110 connected to even-numbered gate lines and another ALS driver 130 connected to odd-numbered ALS lines are disposed in a right portion of the outer BM.
Accordingly, as ALS lines are additionally formed, a pixel aperture ratio is low and it is difficult to obtain a slim outer BM area. According to the conventional art, sizes of a storage capacitor, a data line, a gate line, and a TFT are reduced or these elements are made transparent to obtain a high aperture ratio. However, since a transparent electrode has a high electric resistance, signal delay is intensively generated when signals are transmitted via circuits.